[meteorite-list] Amateur Astronomers See Comet ISON

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue, 24 Sep 2013 13:40:41 -0700 (PDT)
Message-ID: <201309242040.r8OKeffp029487_at_zagami.jpl.nasa.gov>

http://science.nasa.gov/science-news/science-at-nasa/2013/24sep_ison2/

Amateur Astronomers See Comet ISON
NASA Science News
September 24, 2013

Anticipation is building as Comet ISON approaches the sun for a close
encounter on Thanksgiving Day (Nov. 28). No one knows if the blast of
solar heating ISON receives will turn it into one of the finest comets
in years--or destroy the icy visitor from the outer solar system.

Astronomer Carey Lisse, the head of NASA's Comet ISON Observing
Campaign, hopes that "every telescope on Earth will be trained on the
comet in October and November." He may get his wish. As September comes
to an end, amateur astronomers around the world are already monitoring
the comet.

"Comet ISON is approaching Mars in the pre-dawn sky," explains Lisse.
"It is invisible to the naked eye, but within reach of backyard
telescopes."

"I photographed Comet ISON on Sept. 15th using my 4-inch refractor,"
reports astrophotographer Pete Lawrence of Selsey UK. "The comet's tail
is nicely on view even through this relatively small instrument." image
<http://spaceweather.com/gallery/indiv_upload.php?upload_id=86775>

In Aquadilla, Puerto Rico, astronomer Efrain Morales Rivera saw the
comet on Sept. 14th "rising above the canopy of the rain forest just
minutes before sunrise. I used a 12-inch telescope," he says. image
<http://spaceweather.com/gallery/indiv_upload.php?upload_id=86766>

In mid-September, the approaching comet was glowing like a star of 14th
magnitude. That's dimmer than some forecasters expected.

"Certainly we would love it to be a couple of magnitudes brighter right
now," says researcher Karl Battams of the Naval Research Lab in
Washington, D.C.,"but it's doing just fine. I'd say it's still on course
to become a very eye-catching object."

Battams is especially optimistic about NASA's twin STEREO probes and the
NASA/ESA Solar and Heliospheric Observatory. Those three spacecraft are
equipped with coronagraphs--devices which cover the blinding disk of the
sun to produce an artificial eclipse. The coronagraphs will be able to
see ISON at its brightest when it is making its closest approach to the
sun on Thanksgiving.

[Graph: Comet ISON Light Curve]
The light curve of Comet ISON. The solid line traces the predicted
brightness of the comet; red dots are actual observations. These data
were compiled by Matthew Knight of the Lowell Observatory on Sept. 20,
2013. More <http://www.isoncampaign.org/Present>

If ISON survives its brush with solar fire, sky watchers on Earth might
get an eye-full as well.

Based on the latest images, internationally known comet expert John
Bortle says "ISON appears likely to survive the in-bound leg of its
journey all the way to the Sun. It will probably brighten more slowly
than all the early hype led the public to believe. Nevertheless, Comet
ISON should very briefly become exceptionally bright, at least rivaling
the planet Venus in the hours preceding its closest approach to the sun."

After Thanksgiving (Nov 28th), Comet ISON will emerge from the sun's
glare well-positioned for observers in the northern hemisphere. The
comet's tail will likely be visible to the naked-eye in both the morning
and evening sky throughout December 2013.

A useful point of comparison is Comet Lovejoy, which put on a grand
show after it brushed the sun in 2011. People in the southern
hemisphere still remember the comet's tail stretching halfway across the
night sky. Judging from the brightness of Comet ISON, Matthew Knight of
the Lowell Observatory believes that "ISON is likely a few times bigger
than Lovejoy was, so I am optimistic that Comet ISON will become an
impressive sungrazer."

Because this is Comet ISON's first visit to the inner solar system, no
one can say for sure what will happen. Comets are unpredictable, capable
of fizzling at the last minute even after months of promising activity.

Battams, who has been "burned" before by sungrazing comets, cautions
that "at no point in the next couple of months are we going to know if
Comet ISON will survive or not until we actually observe it with our own
eyes."

"Observations from amateur astronomers are really valuable pieces of the
puzzle for us," adds Battams. "They help us to see how the comet is
evolving."

The NASA Comet ISON Observing Campaign aims to get as many eyes on ISON
as possible. To learn how you can help, visit http://isoncampaign.org.

Credits:

Author: Dr. Tony Phillips
Production editor: Dr. Tony Phillips
Credit: Science at NASA
Received on Tue 24 Sep 2013 04:40:41 PM PDT